Metal article and process of making same.



cnnn E. HUMPHBIES, 0E KEARNEY,NEW JERSEY, essre-nonoro THE coin-ransom nEsEAncn COMPANY, or none rsnann crrr, nnwroan, a conronnrron or NEW spe ime i t nt- Patented Juneiaiait.

YORK.

' METAL ARTICLE-AND PROCESS OF MAKING SAME.

No Drawing.

To all whom it may concern:

Be it known that I, CHAD H. HUMPHRIES, a subject of the King of Great Britain, residing at Kearney, in thecounty of Hudson and State of New Jersey, U. S. A have invented certain new and useful Improvements:

in Metal Articles and Processes of Making Same, of which the following is a specification.

This invention relates to metal articles and processes of making'same; and it comprises an' article of hard, dense metal composed. mainly of tungsten group metal and containing in addition to the tungsten metal a smaller percentage of an interpenetrating integralizing or alloying metal, such uniting metal being advantageously a metal of the class of nickel cobalt, iron or the like, said dense metal having a surface with the unattackable permanent characteristics of a noble metal and said dense metal being of relatively high electrical conductivity; and it further comprises a method of producing such metallic material wherein the metals to be united are first produced in the form of as to secure a definite degree of interpenetration of such metals in such later operations, the powders are mixed in the desired proportions, the mixture is heated in' a plural-- ity of temperaturestages, with a pause at each stage, until a metallic material is. produced which is hard, dense, malleable and of relatively high electrical conductivity, such heating however not being carried far enough to produce a material of microscopical (as distinguished from mechanical) h0- mogeneity and of, high ductility and such material is thereafter worked down to.

swaged or'hammered material; all as more fully hereinafter set forth and as claimed.

While the product and the process of the present invention may be used for other purposes, I shall hereinafter describe more specifically the production of metallic material foruse as contact points or elements for Application filed September at, 1914-. Serial Ito. 863,891

' assemblage is in the necessity for the union of different metallic qualities. For electrical purposes, naturally the contactmaking surface shouldbe of non-oxidizing (or noble) metal to insure quick and positive making and breaking ofthe circuit. Any

of oxid or impairment of the bright metallic surface militates against positive metallic contact. Further, the surface should be of high melting metal and be relatively hard and permanent to avoid mechanical wear and electrical erosion. The body of the contact element must be mechanically strong and hard to secure it in permanent union with the holding element; and for this purpose it is also highly desirable that it be of such character as to permit striking up or riveting in place. Conditions of use in modern electrical devices and machinery are frequently so severe as to require great strength and rigid attachment in these contacts; a type of attachment best secured by a rivet union. 4

No single metallic material available at present possesses all these qualities to a sufficient degree. Platinum possesses the noble surface, but it is relatively soft, even when alloyed with iridium, etc., and wears electrically and mechanically, while it is not a strong metal. It is alsoan expensive material. Tungsten, as at present produced,

" while high melting and hard and strong oxidizes to some extent and moreover is not sufficiently workable to permit striking-it up to form a riveted unionwith a holding element.

In the present art therefore high grade contact elements are customarily made of two or more metals and are not made of a single piece of one metal. The best are made by weld uniting a facing layer ofplatinum toa shank of nickel, the platinum giving the permanent surface and the nickel the strength.

I have found that I can produce a composite metallic material from which strong, noble-surfaced rivetable contact points can be made and which is'also applicable to many other purposes requiring incorrodible acid proof strong metal, such as tooth pins,

commutator segments, anodes, jewelry, etc.

To this end, I produce a material which though mainly tungsten contains another or integralizing metal-bonding and qualifying the tungsten in a special way. This second metal is a metal of the iron class such as cobalt or iron. Nickel is much the best.

The proportion of tungsten in the completed material is best around 85 to 95 per cent. For some purposes it is advantageous to have some molybdenum. The present method may indeed be applied to the manufacture of composite molybdenum articles containing small proportions of tungsten or no tungsten. Mo ybdenum is a hard strong metal of much the same character as tungsten and although it oxidizes somewhat more easily the 0nd volatilizes with compara tive readiness and in situations where the oxids tend to form, as on hot contact points, it tends to disappear as readily. A small proportion, say 0.5 to 3 per cent. of molybdenum used with tungsten, makes a materi al of even more noble characteristics than the tungsten alone.

While tungsten is, by present methods, not readily worked to produce articles of the character here desired, I have found that by the present method I can make a material which is mainly tungsten and is hard, dense, conductive and sufficiently malleable for the present purposes. It possesses the valuable properties of tungsten as prepared by the best methods now in use and in an enhanced degree. This material while not ductile in the sense of being readily drawn down to wire, can be swaged and worked to produce bodies of com act metal suitable for contact points, .toot -pins, etc. When formed into a contact point it is sufliciently sworkable to allow heading up or riveting into place .something which cannot be done with the present grades of-tungsten. y

'In preparing mymaterial I use fine powdered tungsten of cryptocrystalline or semi-amorphous character. It is best that it be sufficiently fine' to pass through a two hundred mesh'sieve but not be completely impalpable 'or of colloid character. best material for my purpose is of dark gray rather than light gray color, and is free of perceptible brownish spots or hue. The material may have a slight brownish cast but.

is best not distinctly brown. A coarser powder requires a longer heating period than the times hereinafter indicated and othermodifications in conditions of operations; and I shall hereinafter refer more particularly to a powder of the indicated character. The tungsten is best not coarsely crystalline. It need not be perfectly pure, a certain amount of impurities indeed appearing to facilitate the operation in the specific method hereinafter described. It may be made by reduction from commercial tungstic oxid (or tungstic acid) by hydrogen. The commercial grade of tungstic acid is suitable. One oxid which I have used with. advantage contains about 0.2 per cent. of alkalis and about the same amount of phosphoric acid. To make a suitable metal this crude oxid can be reduced by hydrogen in any suitable reduction furnace, care being taken that the temperature rises quite slowly during the operation and that the metal remains amorphous without becoming-coarse and crystalline. The reduction is ordinarily not carried to the point of the complete disappearance of oxygen, a small amount of oxygen being left in the material.

With this tungsten I mix finely divided nickel or similarmetal, which may be obtained by reduction in-a similar manner. Nickel oxid or oxalate may be reduced at a low temperature. Reduction of oxid by hydrogen may be performed in any suitable type of apparatus. In reduction the temperature should not rise quickly enough to make the-.metal coarse grained. It should be as aniiqf gphous and fine grained as possible.- A perceptible grain size is not'here, as in the case of tungsten, desirable; the nickel should be completely impalpable. Metal producedfrom the oxalate is finer than that from the oxid. Reduction of the OXld by hydrogen may be performed around 300 Reduction is ordinarily interrupted at a point where some oxygen still remains; say not over 2 per cent. This reduction results in the formation of a velvety black and indefinitely finepowder of metallic nickel which is often pyrophoric. Therefore care should be taken in handling.

The two metals are very carefully mixed in the desired proportions. For making contact points and like-purposes, a mixture of 85 per cent. to 95 per cent. tungsten and 15 to 5 per cent. nickel makes a useful material. A material of 6 to 8 per cent. is ordinarily employed in making contact points for general purposes. In obtaining such material a little more nickel is ordinarily used (say a few tenths per cent.) than is desired in the final material to allow for ,losses by volatilization. As to the amount of this allowance however much depends on the care with which the operation is carried out...

The mixed metals are next formed into bars or slabs in a steel mold by heavy hydraulic pressure. To facilitate this shaping a little temporary binder, such as a solution of camphor in ether, may be advantageously used. For example, a bar'of square cross section one quarter inch on the side and 8 inches long may be made by heavily pressing about'85 grams of the described mixture. It is desirable in the present rocess with the specific procedure hereina ter indicated, to work with shaped bodies of about this order. of magnitude. Other dimensions or shapes require some changes in the time and temperatures hereinafter set forth. The bar or slug is now sintered in a hydrogen atmosphere. During this operation it may rest on a nickel supi naaaeoo port. Heating: which may be by fire heat,

should be gradual to prevent disruption by volatilization or carbonization of the binder, if a binder be used. The best temperature T have found is from 800 to 1100 C. and the treatment may be for about ten minutes. The slug is then allowed to cool in an atmosphere of hydrogen or other nonoxidizing atmosphere. After cooling it will be found to have changed from a dark to a light gray color and to present the appearance of a hard coked mass. It is not ductile and on the contrary it is exceedingly brittemperature for about five minutes.

'tle, easily breaking into pieces. This sintered slug or billet is next heated in a plurality of temperature stages with apause at each stage- Heating may now be effected by an electric current passsed through the slug andshould take place in an atmosphere containing hydrogen. should be to about 1200. (3., the tempora ture being maintained as nearly at this point as practicable. The slug may be held at (this no purpose of this operation is to cause an elimination of impurities contained in the tungsten. and nickel. These impurities are alkalis, phosphoric acid, etc. Oxygen is also substantially removed. During this heating operation the impurities volatilize and form a sort of fog, giving 'a distinct tint to the flame if escaping hydrogen be ignited. About five minutes heating at this temperature is ordinarily suficient to cause the disappearance of most of the fog vwiththe slug described. This heating may be called the purifying stage. The temperature is then again raised, this time to about 14.00 C. This temperature should be maintained as nearly as practicable and it is best to conduct the operation with the aid of an optical or other high-temperature pyrom eter. In this heating stage the mass shrinks considerably and traces, of impurities are eliminated. Heating is in an atmosphere containing hydrogen. This heating stage may be called the shrinking stage and ordinarily requires about 5 minutes. The shrunk billet is now raised in temperature, this time to about 1600. The exact temperature required will vary somewhat with the percentage of nickel in the mixture and other conditions. At this temperature nickel is freely fluid. Heating may be continued for about five minutes. This heating which may be called the integralizing stage has for its purpose union of the tungsten and nickel and the production of a hard, dense metal body which can 'be swaged. In this union the nickel and tungsten alloy and interpenetrate to a large extent.

In working with the nickel-tungsten mixture described, containing 6 to 8 per cent. nickel, the directions just given should be adhered to quite closely as regards tempera- The first heatin tures and times, since otherwise the results are not dependable and the final billets may be unworkable. With higher proportions of nickel the final temperature should be somewhat lowered. Too long a finalheating or too fine or too coarse grained a tungsten give a non-swageable material, with the specific process now under description.

The material obtained after the integralizing stage upon cooling is not ductile in the sensein which the word is usually employed and it cannot be bent cold without causing fracture. Examined under the microscope it is seen to be fine grained and dense in texture. The billet of this material now may be swaged or rolled down to smaller size, becoming more compact, tenacious and hard wth each working. Either hot or cold swaging may be used; and annealing may be resorted to.

' In hot swaging, the finished slug may be reheated to 1200 to 1500 0., the temperature depending on the composition. With the material containing 6 to 8 per cent. nickel about 14=0O is best. It is then taken to a high speed swaging maehinegiving,

say, 5000 blows per minute and worked down, being reheated at intervals. As the operation progresses the temperature may drop and the speed of the swaging machine may be increased finally becoming, say, 7000 blows. In making contact elements, the reduction of the stated slug may be to a round body of, say, 0.16 to 0.125 inch- Pieces of this round body or rod of suitable length may next be given a shank bygrinding or cutting. As the metal is quite hard this shank making operation may advantageously be efi'ected by an emery or carborundum Wheel. If the contact element is tobe mounted in an orificed metal holding element, such as a spring, which is usually the case, the shank should be made to give a tight fit with the orifice. On assembling the contact element with the holding element, the protruding end ofthe shank may each 3 or 5 passes, or after a reduction of,

say, 0.025 inch in diameter.

Metal produced as described is sufficiently malleable to permit swaging as described; and also topermit heading up to give a firm, permanent and secure rivetlike union with a holding element. In so heading up the fiber of the metal permits the formation of the head. i

r A metal with 6 to 8 per cent. nickel and the res due tungsten has a melting point higher than that of platinum and sufiers little erosion or wear when used for elec-.

trical purposes. It is also much harder than platinum or platinum-iridium alloys and wears much better. It does not have the tendency to film over with a'skin of oxid which is displayed by pure tungsten. It is exceedingly acid-reslstant making 'it particularly suitable for tooth-pins, anodes, etc.

In the foregoing method, iron or cobalt,

may be used in lieu of the nickel either in whole or in part, but I find nickel or its alloys to be well adapted. With these other metals, the indicated temperatures, etc.,

method an intimate mixture of fine-grained tungsten powder with a small amount of another pulveriform metal of lower melting point (best, nickel) is heated progressively in discrete temperature stages, with the final heating at a temperature at which the binder metal is capable of being freely liquid but far below that at which the tungsten particles themselves will melt. This temperature is also far below that at which an alloy of the two metals in the chosen proportions will liquefy. This heating is interrupted at a time when the metallic mass becomes unified or integralized by interpenetration of the two metals sufficiently to allow the mass to be worked down. Continuance of the mutual action of the tungsten and bonding metal upon each other results in the production of a material which is more in the nature of a true alloy and which has properties of a type not here desired. The present material is more in the nature of a bonded body of tungsten.

Owing to the fine grained, dense, nonporous character of the final product produced after swaging down, and the intimate aaaeeo 1 all ordinary cutting tools. In this treatment it may be raised to, say, 1600 C. and I then suddenly cooled by'immersion in water.

What I claim is 1. As a new material, a hard, dense relatively conductive, mechanically homogeneous fineained metallic mass mainly composed 0 particles of a metal of the tungsten class but also containin bonding metal of lower meltmg' point, said mass being substantially non-ductile but malleable to an extent which will permit swaging hot or cold.

another and 4 2. As a new'material, a hard, dense. relatively conductive, mechanically homogeneous fine-grained metallic mass mainly composed of particles of tungsten but also containin another and bon metal of lower me ting point, said mass" being substantially non-ductile but malleable to an exltgnt which will permit swaging hot or co v 3. As a new material, a hard, dense'relatively conductive, mechanically homogeneous fine-grained metallic mass mainly composed of particles of a metal of the tungsten class but also containing a little nickel as a bonding material, said mass being substantially non-ductile but malleable to an exfint which will permit swaging hot or co 4:- As a new material, a hard, dense relatively conductive, mechanically homogeneous fine-grained metallic mass mainly composed of particles of tungsten but also containing a little nickel as a bon mate rial, said mass being substantially non-ductile but malleable to an extent which will permit swaging hot or cold.

5. As a new material, a metallic mass comdense hard malleable but substantially 'npri ductile body.

6. As a new material, a metallic mass composed of particles of fine-grained tungsten bonded and united by a relatively small amount of nickel in a dense-hard malleable but substantially non-ductile body.

7. In the manufacture of tungsten materials, the process which comprises mixing a finely grained metal of the tungsten class with another metal of lower melting point, heating the mixture to a temperature at which said other metal is freely fluid and holding at this temperature sufliciently long to permit a limited degree of interpenetration without complete alloying of the two metals.

8. In the manufacture of tungsten materials, the process which comprises m1x1n finely grained tungsten with another meta tltt of lower melting point, heatin the mixture other metal.v

to a temperature at which sai is freely fluid and holding at this temperature sutliciently long topermit a limited degree of interpenetration without complete alloying of the two metals.

9. In the manufacture of tungsten materials, the rocess which comprises mixing a finely' gralned metal of the tungsten class with nlckel, heating the mixture to a temperature at which said nickel is freely fluid and holding at this temperature sufiiciently long to permit a limited degree of interpenetration without complete alloying of the two metals.

10. In the manufacture of tungsten materials, the process which comprises mixing finely grained tungsten with nickel, heating the mixture to a temperature'at which said nickel is freely fluid and holding at this temperature sufliciently long to permit a limited degree of interpenetration without complete alloyin of the two metals.

11. In the pro uctionof hard, dense tungsten materials, the process which comprises intimately mixing fine-grained tungsten with a pulveriform metal of the iron class and heating the mixture at a temperature at which said metal is freely liquid but below the melting point of tungsten and below the melting point of an alloy containing tungsten and said other'metal in the same pro: portion, said heating being interrupted when the mass becomes malleable enough to swage and before any substantial alloying has taken place.

' 12. In the production of hard, dense tung sten materials, the process which comprises intimately mixing fine-grained tungsten with pulveriform nickel and heating the 'mixture at a temperature at which said nickel is freely liquid and below the melting point of tungsten and below the melting point of an alloy containing tungsten and said nickel in the same proportion, said heating being interrupted when the mass becomes malleable enough to swage.

13. In the manufacture of composite tungsten articles, the process which comprises mixing fine-grained tungsten with a minor amount of a lower meltingpulveriform metal of the iron class, heating the mass sufficiently to sinter it, continuing the heating after the sintering and elevating the temperature sufiiciently to eliminate impurities, and then elevating the temperature to a point above the melting polnt of the other metal, heatin at thistemperature being continued untll the mass becomes malleable enough to swage.

14. In the manufacture of composite tungsten articles, the process which comprises heating after the sintering and elevating the temperature sufiiciently to eliminate impurities, and then elevating the temperature to a point above the melting point of the nickel, heating at this temperature being continued until themass becomes malleable enough to swage.

15. In the manufacture of composite tungsten articles, the process which comprises mixing fine-grained tungsten with a pulveriform bonding metal, heating the mixture to a temperature at which it will sinter, further heating the mixture at about 1200 C. until contained impurities are substantially removed and elevating the temperature to a point at which the bonding metal-is freely fluid, the last stated heating being continued until the mass becomes malleable enough to swage! v 16. In the manufacture of composite tungsten articles, the process which comprises mixing fine-grained tungsten with pulveriform nickel, heatingthe mixture to a temperature at which it will sinter, further heating the mixture'at about 1200 CLuntil contained impurities are substantially removed and finally elevating the temperature to about 1600 0., this temperature being maintained until the mass becomes malleable enough to swage.

17 In the manufacture of composite tungsten articles, the process which comprises sintering an intimate mixture of fine-grained meltingbonding metal, heating the sintered mass to a temperature at which volatile imtungsten with a minor amount of nickel,

heating the sintered mass to a temperature at which volatile impurities will be disp'elled,.heating the purified mass to a higher temperature to shrink it, and finally heating the shrunk mass to a temperature about 1600 0., the heating being continued until the mass becomes malleable enough to swage.

19. In the manufacture of composite tungsten articles, the process which comprises heating a sintered intimate mixture of finegrained tungten and fine-grained nickel to a temperature at which the nickel is freely fluid, heating at this temperature being continued until a sufficient degree of interpenetration of the metals is secured to make the mass malleable enough to swage.

20. In the manufacture of composite tungsten articles, the process which comprises tungsten with a minor amount of a lower are sintering an intimate mixture of fine-grained tungsten and fine-grained nickel, purifying the sintered mass by elevating the temperature suficiently to volatilize impurities, after maintaining at such' volatilization temperature for a sufiicient 1e h of time heating to a temperature at w 'eh the mass will shrink and become compact, after maintaining the heat at such shrinking temperature for a sufiicient length of time elevating the temperature to around 1600 C. animaintainingthe temperature at this oint until the mass becomes malleable enoug to swage. I 21. In the manufacture'of composite tungsten articles, the producing an intimate mixture of finemg a small process which comprises grained tungsten and fine-grained nickel, both such tungsten and such nickel containproportion of residual oxid, smtering the mass, heating. to a temperature at whic impurities willfvolatilize, heating to a temperature at which the mass will shrink and finally heating to about 1600 C. until the mass becomes malleable enough to swage. a a

In testimony whereof, I aflix my signature in the presence of two subscribing witnesses. A CHAD H. HUMPHRIES. Witnesses:

M; J. MAonoNaLn, .Gnonon P. Scrronn. 

